1. Field of the Invention
The present invention generally relates to a liquid crystal display (LCD) device provided with a gas detector, a gas detector for use in such a liquid crystal display device, and a method for manufacturing such a gas detector.
2. Description of Related Art
LCD-displays are known in the art. An LCD-display has a number of pixel elements, usually arranged in a matrix formation, wherein each pixel element may be controlled individually to emit light. By selectively controlling each pixel, an image may be created.
The LCD-display may be formed by a stack of layers, which will be explained in more detail below with reference to FIG. 1. One of these layers contains liquid crystal molecules forming a liquid crystal element which may be controlled by electrode layers, e.g. an Indium Tin Oxide layer (ITO-layer), arranged to address specific regions (pixels) of the liquid crystal element by applying a voltage to these specific regions.
By controlling the application of a voltage, the orientation of the molecules of the liquid crystal may be controlled in such a way that the liquid crystal element is either in an opaque state, in a transparent state or in some defined semi-transparent state in between. The transmission properties of the stack of layers may be controlled spatially by means of a grid of electrodes. By applying a voltage on one or more electrodes within the grid of electrodes, the transmissivity of pixels is addressed.
The liquid crystal element and the electrode layers are positioned between two polarizing filters. Light traveling through the stack of layers may be blocked or transmitted depending on the orientation of the liquid crystal molecules and the orientation of the polarizing filters.
In order to create a color LCD-display, each pixel may be divided into sub-pixels that may be individually addressed, each sub-pixel having its own liquid crystal element. Each pixel may be divided according to a red, green, blue (RGB) arrangement, i.e. each pixel may be divided into at least a red, a green and a blue sub-pixel, as known to a person skilled in the art. The colors are added to the arrangement by adding a separate color filter layer, for example, between the polarizing layers. The color filter layer may be a matrix of adjacent color filters.
LCD-displays are currently used in numerous mobile applications, e.g. mobile telephones, personal digital assistants (PDA's), navigation tools etc. While on the move, a user of a mobile application may enter an area with a dangerous concentration of a hazardous gas, e.g. carbon monoxide. Carbon monoxide (CO) is a colorless and odorless gas. Its affinity to bind to hemoglobin far exceeds the binding affinity of oxygen. Consequently, exposure to CO reduces the oxygen carrying capacity of blood. Low level exposure can cause flu-like symptoms, while higher level exposure may cause severe headaches and fainting. Higher level exposure over a considerable amount of time can be lethal.
With the continual increase of mobile communication and an increase in locations where people go for work, recreation etc., there is a need to reduce the risk of encountering an environment where dangerous concentrations of one or more hazardous gases are present.